A device for measuring various biological information is conventionally known. As a device for measuring the biological information, for example in a body composition measurement device, a method of measuring the impedance of a body to calculate a body composition value from the difference in electrical characteristics of the fat and the muscle is known for an estimating method of a body fat percentage, a subcutaneous fat percentage, or the like. The estimation equation of the body composition is calculated from a correlation of the measurement data from, for example, MRI, CT scan, and DEXA of a great number of subjects, and the impedance value.
As such, there is proposed a method of estimating the body composition such as muscle amount from the measurement value of the impedance using the estimation equation created by a regression analysis based on the data collected in advance with the MRI (see Patent Document 1).
However, the estimation error may occur since the electrical characteristics differ among people in some degree. In particular, the estimation error tends to become large in children and athletes.    Patent Document 1: International Patent Publication 2002/43586